Wheel Loader Hydraulic Priority Valve for Stable Steering Flow
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Solution Overview
Problem
Off-road construction vehicles face challenges in efficiently managing hydraulic flow between steering and implement functions, leading to stability issues and energy inefficiencies due to shared pump flow, with existing systems lacking effective solutions for shock suppression and optimal energy utilization.
Innovation Solution
A hydraulic system with integrated priority and auxiliary circuits, featuring a priority valve proportional to steering commands, a pressure reducing valve, and electronic control, which distributes flow efficiently between steering and implement functions, using a single or multiple pumps to prioritize steering while optimizing energy use and minimizing system disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pump supplies hydraulic fluid to both steering and auxiliary functions, then device complexity is reduced, but steering stability deteriorates due to shock and oscillation
Solution Approach 1:
The hydraulic system is segmented into separate priority and auxiliary circuits, each with dedicated flow control. The priority circuit receives regulated flow from the pump first, ensuring steering stability, while the auxiliary circuit receives remaining flow. This segmentation prevents shock and oscillation in the steering system while maintaining operational simplicity.
2Productivity
If hydraulic fluid is directed to auxiliary functions first, then auxiliary function performance is improved, but steering control is compromised due to fluid pressure drop
Solution Approach 1:
The priority valve performs preliminary action by directing hydraulic fluid to the steering system first before allowing flow to auxiliary functions. The valve spool is positioned to establish priority flow paths in advance, ensuring steering control is maintained while enabling auxiliary functions when steering demands are low.
3Reliability
If a priority valve is used to give precedence to steering system, then steering reliability is improved, but energy efficiency deteriorates due to excess fluid power output being wasted
Solution Approach 1:
The pressure compensator provides feedback by sensing the hydraulic steering load and adjusting the priority valve operation accordingly. When steering load is low, the system allows auxiliary functions to operate; when steering load increases, the priority valve automatically redirects flow to steering, preventing energy waste while maintaining reliability.
Solution Approach 2:
The system changes operational parameters dynamically by using a pressure compensator to sense load conditions and adjust flow distribution. The priority valve spool position changes based on pressure differential, allowing the system to adapt between prioritizing steering and allowing auxiliary functions, thereby reducing energy loss.
4Loss of energy
If pump flow is shared between steering and implement systems, then energy efficiency is improved, but system response deteriorates due to flow division compromising performance
Solution Approach 1:
The priority valve creates a dynamic flow distribution system where the spool position continuously adjusts based on steering load and auxiliary function demands. This dynamic operation allows the system to optimize between energy efficiency and response speed by automatically prioritizing steering when needed while enabling auxiliary functions during normal operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system ensures stable and efficient hydraulic flow distribution, suppressing steering shocks, maintaining operator control, and enhancing energy efficiency by prioritizing steering functions while optimizing pump flow, thereby improving productivity and reducing energy losses.
Implementation Method 1
the priority valve includes a valve spool acted upon by fluid pressure to overcome a spring and assume a first spool position
Implementation Method 2
the valve spool acted upon by fluid pressure to overcome a spring
Implementation Method 3
hydraulic control systems for steering and auxiliary functions in off-road vehicles
Data Source
AI summary
A hydraulic system for a work machine comprising a priority circuit including at least a first priority actuator and a priority control valve for controlling the supply of hydraulic fluid to the first priority actuator and for providing a load sense signal indicative of the load acting on the first priority actuator; an auxiliary circuit including at least a first auxiliary actuator and at least a first auxiliary control valve for controlling the supply of hydraulic fluid to the first auxiliary actuator; at least a first pump for producing a flow of hydraulic fluid; and a priority valve for distributing the flow from the pump to the priority circuit and auxiliary circuit for operating the respective actuators thereof, with priority being given to the priority circuit as a function of the load sense signal.